Equity Research interview preparation
Sell side and buy side. Every question is either traced to a named firm from a public candidate report, or tagged at desk level when we could not trace it. Answers lead with the point, then the mechanism, then the limitation.
100 questions, mapped to the firms that asked them
- Questions
- 100
- Traced to a firm
- 72
- Firms
- 45
- Updated
- September 2026
038What is the rule of forty, and what are its weaknesses?Technology coverageGrowth equity
Say this
Revenue growth plus profit margin should exceed 40. It says a software company can be forgiven for losing money if it is growing fast, or for growing slowly if it is profitable, but not both.
Then walk it
- The logic is a trade-off: spending on growth suppresses margin, so the combined figure measures whether that spend is productive.
- The first weakness is the margin definition. Free cash flow margin, operating margin and EBITDA margin give very different scores for the same company, and firms naturally quote the flattering one.
- The second is that it treats a growth point and a margin point as equivalent. They are not: for a long-duration asset, a point of durable growth is worth far more than a point of margin, because it compounds.
- The third is that it ignores the quality of the growth. Growth bought through acquisitions, or through discounting that damages net retention, scores the same as organic growth from pricing.
- And it says nothing about durability. A company at 60 today that decelerates sharply next year is worth less than a steady 42.
- So I would use it as a screen to compare companies quickly, never as a valuation input. The valuation question is always durability, and the rule of forty is silent on it.
Where candidates lose it
Quoting the heuristic without a critique. Anyone can state it. Naming the margin-definition problem and the growth-versus-margin asymmetry is what shows you have used it rather than read it.
Expect next
- Which margin would you use?
- Would you rather have 20 percent growth at 20 percent margin, or 40 percent growth at breakeven?
- How do you assess durability of growth?
074How would you analyse an IT services company?Credit SuisseInvestment Banking · Mumbai · 2021
Say this
It is a people business, so the drivers are headcount, utilisation, billing rate and attrition. Revenue is headcount times utilisation times realisation, and margin is driven by the pyramid and the offshore mix.
Then walk it
- Revenue build: billable headcount times utilisation times realised rate per hour. Constant-currency growth is the number the market watches, because reported growth is distorted by the dollar-rupee rate.
- Margin drivers: the employee pyramid, meaning the ratio of juniors to seniors, the onsite-offshore mix, utilisation, and wage inflation. A steeper pyramid and more offshore work both lift margin.
- Attrition is the key operational metric. High attrition means replacement hiring at higher wages, backfilling with less experienced staff, and delivery risk on fixed-price contracts.
- Demand indicators: total contract value of deals signed, the book-to-bill ratio, and the pipeline. Deal wins lead revenue by several quarters, so this is where the variant view usually sits.
- Client concentration and vertical mix matter: exposure to banking and financial services means the cycle in client budgets flows straight through.
- The structural question now is what AI does to the model. If delivery becomes less headcount-linked, the revenue build breaks and the pricing model shifts from effort to outcome. That is the live debate and having a view on it is what makes the answer current.
Where candidates lose it
Modelling it as a generic services business with a growth rate. The sector has a specific vocabulary, utilisation, pyramid, realisation, attrition, constant currency, and an interviewer covering it will expect all of them.
Expect next
- What does AI do to the headcount-linked revenue model?
- Why does constant currency matter?
- How does the rupee affect margins?
Reported by candidates at Credit Suisse (Investment Banking, Mumbai, 2021). Source: Wall Street Oasis.
Firm tags come from public, anonymous candidate reports on Wall Street Oasis: strong signal, not sworn testimony. Firms are named as the places a question was reported, not as partners of Fin Maverick. Answers are written for this page to show how to think out loud; they are not scripts to recite.

